Damage to the teats of dairy cows through the use of milking machines causes substantial economic loss to the dairy industry. These losses occur from physical teat damage, increased incidence of mastitis, and increased culling rates.
Typical milking machines comprise a teat cup that includes a hollow, rigid outer shell or sleeve having a port that is adapted to be attached to a pulsating vacuum line. A resilient, tubular liner or inflation typically extends from a top to a bottom of the sleeve, concentrically disposed within the shell. The ends of the inflation make sealing engagement with the shell to form an annular vacuum chamber between the shell and the inflation. The pressure in the annular chamber is alternated between a lower pressure, typically a sub-atmospheric pressure, and a higher pressure, typically atmospheric, by the pulsating vacuum line attached to the shell at the port. A milk-collecting vacuum line is connected to a milk-receiving cup attached to the shell and in communication with the interior of the inflation, positioned at the lower end of the inflation. This line is to draw milk from the cow's teat and convey it to a collection tank. The valve distal opening of the milking system is received through an upper end of the inflation. The interior of the inflation is maintained at a sub-atmospheric pressure, and the alternating pressure in the annular chamber periodically forces the walls of the inflation outwardly and inwardly resulting in a massaging action on the teat as well as periodically collapsing the walls of the inflation below the teat. The collapse of the inflation periodically relieves the teat from exposure to the vacuum within the inflation due to the negative pressure in the milk-collecting vacuum line. The teat cup is made heavy enough that it draws the teat downward, and the combination of the effects of the weight of the teat cup and the variation of geometry of the inflation and variation of the amount of vacuum to which the teat is exposed, causes the inflation to ride up and down on the teat by a small amount. Such systems exert damaging physical and vacuum pressure on the teat and cause the teat to be immersed in milk that can contain bacteria washed off of the surface of the teat and udder.
As cows are genetically selected to produce more milk, standard machine milking time is increased. Each time a cow is milked, severe mechanical forces of vacuum and physical pressure are exerted on the teat and its structures. These adverse forces can cause skin damage to the teat, teat end erosions, and hyperkeratosis.
Irritations of the teat and teat canal ultimately increase the cow's risk of mastitis infections and decrease her lifetime productivity within the herd. During the standard milking process, the teat end of the cow is continually bathed in milk. Microorganisms on the teat of the cow are washed into the milk stream and can be injected into the teat canal via the repeated inflation/deflation cycles of the automatic milking machine. These microorganisms can cause mastitis. Clinical mastitis cases can cost as much as $300.00 per episode and subclinical mastitis greatly reduces milk production within a herd.
Additionally, increased culling rates of dairy cattle due to mastitis infections can cripple the financial performance of a dairy farm. Culling rates can easily exceed the capacity of the herd to sustain itself thus forcing the dairyman to purchase additional animals to maintain the herd at a desired number of animals.
Accordingly, what is needed is a milking system that results in less damage to the cow's teat and that reduces exposure of the mammary gland to infective agents. It would also be desirable to decrease the time required for milking.